Single Antenna Interference Cancellation via GMSK De-rotation
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Solution Overview
Problem
In GSM communication networks, co-channel interference limits system capacity due to the inability to effectively mitigate colored interference with a single receive antenna, as existing methods like interference whitening techniques are not applicable.
Innovation Solution
The implementation of a single antenna interference cancellation (SAIC) method using mono interference cancellation (MIC) branch combining (MIC-BRC) processors, which de-rotate GMSK signals, adjust filter lengths based on interference conditions, and apply maximum-likelihood sequence estimation (MLSE) equalization to reduce residue errors and improve signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If interference whitening technique is used, then interference mitigation is improved, but it cannot be applied to single antenna systems
Solution Approach 1:
The patent transforms the GMSK signal from its original form into a BPSK-like representation by exploiting the structure of GMSK modulation. This dimensional transformation allows the signal to be processed in a way that creates virtual signal paths, enabling interference whitening techniques to work effectively even with a single physical antenna. The key is treating the in-phase and quadrature components as separate dimensions that can be processed independently.
Solution Approach 2:
The patent introduces an intermediary processing stage that de-rotates the GMSK signal and separates it into components that can be treated as multiple virtual channels. This intermediary transformation layer allows the system to apply multi-antenna interference mitigation techniques to a single-antenna system by creating virtual diversity through signal processing rather than physical antenna diversity.
2Object-affected harmful factors
If multiple receive antennas are used, then interference mitigation is improved, but device complexity increases
Solution Approach 1:
The patent creates virtual copies of the received signal by de-rotating and processing the GMSK signal into multiple components that mimic the behavior of signals received from multiple antennas. Instead of using multiple physical antennas, the system creates virtual signal paths through mathematical transformations, achieving diversity gain without the hardware complexity of multiple antennas.
Solution Approach 2:
The patent changes the parameters of the received signal through de-rotation and component separation, transforming the GMSK signal into a form that exhibits properties similar to BPSK signals. This parameter transformation allows the system to exploit signal structure rather than hardware diversity, reducing complexity while maintaining interference mitigation performance.
3Adaptability or versatility
If BPSK approximation is used, then SAIC feasibility is improved, but signal accuracy may be reduced
Solution Approach 1:
The patent carefully controls the approximation by de-rotating the GMSK signal and processing it in a way that preserves the essential signal characteristics while enabling BPSK-like processing. The approximation is applied selectively to enable SAIC functionality without completely sacrificing signal fidelity, achieving a balance between feasibility and accuracy through controlled parameter transformation.
Data Source
AI summary
An interference cancellation (IC) processor, a method, a method of manufacturing a semiconductor device, and a method of constructing an integrated circuit are provided. The IC processor includes a plurality of mono interference cancellation (MIC) filter estimation processors; a combined effective channel calculation processor; a combined filter calculation processor; and a combined filter processor, including a first input connected to the output of the combined filter calculation processor, a second input for receiving a signal for setting a length of the combined filter that is connected to a second input of the IC processor, a third input connected to the input of the MIC-BRC processor, and an output for providing a filtered output of a de-rotated GMSK signal that is connected to a second output of the IC processor that provides a filtered output yi of the de-rotated GMSK signal.